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Reports <code>equals()</code> calls on <code>StringBuilder</code>, <code>StringBuffer</code> and instances of
<code>java.util.concurrent.atomic</code> package.
<p>The <code>equals()</code> method is not overridden in these classes, so it may return <code>false</code> even when the contents of the
  two objects are the same.
  If the reference equality is intended, it's better to use <code>==</code> to avoid confusion.</p>
A quick-fix for <code>StringBuilder</code>, <code>StringBuffer</code>, <code>AtomicBoolean</code>,
<code>AtomicInteger</code>, <code>AtomicBoolean</code> and <code>AtomicLong</code> is available
to transform into a comparison of contents.
The quick-fix may change the semantics when one of the instances is null.
<p>Example:</p>
<pre><code>
  public void test(StringBuilder sb1, StringBuilder sb2) {
    boolean result = sb1.equals(sb2); // Suspicious
  }
</code></pre>
<p>After the quick-fix is applied:</p>
<pre><code>
  public void test(StringBuilder sb1, StringBuilder sb2) {
      boolean result = sb1.toString().equals(sb2.toString());
  }
</code></pre>
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<p><small>New in 2017.2</small></p>
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